17 alpha ethynylestradiol and norgestrel in combination induce micronucleus increases and aneuploidy in human lymphocyte and fibroblast cultures

Oral contraceptives are highly efficient and easily administered drugs; how ever, it must not be forgotten that they are composed of chemical substance s which can be classified as potential carcinogens. Testing of a substance for genotoxicity represents a reliable approach both to evaluate the geneti c hazard and to obtain information on its possible tumorigenic (cancerogeni c) properties. The present study was undertaken to evaluate through careful ly planned and controlled investigations the in vitro cytogenetic effects o f oral contraceptives (ethynilestradiol and norgestrel mixed in the proport ion 1:5) using three different concentrations, with two different durations of treatment (48 and 72 h), on two types of human cells (lymphocytes and f ibroblasts) and a series of short-term test procedures: sister chromatid ex change (SCE), micronucleus test (MN), and chromosome aberrations (CA). In a ddition, the FISH procedure and in vitro anaphase and metaphase preparation analyses were performed. In contrast to CA and SCE frequencies, the freque ncy of MN in treated blood lymphocytes showed higher values by comparison w ith the controls,although the difference was statistically significant only for the lowest concentration (P = 0.016). When using pancentromeric alphoi d probes, the FISH procedure gave positive signals in more than 85% of micr onuclei, clearly indicating that MN may contain whole chromosomes rather th an acentric fragments. Unlike the lymphocytes, the fibroblasts showed dose- dependent effects, although those treated with the highest hormone concentr ations showed an increased number of highly damaged cells (cytoplasmatic va cuolization, nuclear fragmentation, etc.), a decreased number of anaphase c ells, a large number of which were abnormal, and a reduction of mitotic ind ex. In conclusion, our data confirm that hormones do not induce structural chromosome aberrations in lymphocytes and indicate that ethynilestradiol an d norgestrel have an aneugenic effect on fibroblast and lymphocyte cultures ; FISH analysis on micronuclei from lymphocyte cultures and anaphase prepar ations from fibroblast cultures support this hypothesis. (C) 2000 Wiley-Lis s, Inc.